diff --git a/src/route/nexthop-list.hpp b/src/route/nexthop-list.hpp
index b35f3bf..1c35079 100644
--- a/src/route/nexthop-list.hpp
+++ b/src/route/nexthop-list.hpp
@@ -27,7 +27,6 @@
 #include <set>
 #include <iostream>
 #include <boost/cstdint.hpp>
-
 #include <ndn-cxx/face.hpp>
 
 namespace nlsr {
@@ -140,6 +139,9 @@
 bool
 operator==(const NexthopList& lhs, const NexthopList& rhs);
 
+bool
+operator!=(const NexthopList& lhs, const NexthopList& rhs);
+
 std::ostream&
 operator<<(std::ostream& os, const NexthopList& nhl);